Suturing of tissues and organs representing a basic stage of surgical intervention greatly influences the possibilities and results of surgical operations. At the same time, the stapling procedure largely depends on technical facilities, and, particularly, on the design of the surgical stapling apparatus that would provide a means for making high-quality sutures easily without damaging adjacent tissues and organs, and would permit compensating the growing staple forming forces.
Known in the art is a surgical stapling apparatus (for example, cf. U.S. Pat. No. 3,079,606).
The prior-art surgical stapling apparatus comprises a thrust and a staple cases linked by a sectional joint and a detent. The staple case comprises a working section incorporating staple grooves arranged across a longitudinal axis of the staple case. The staple grooves contain U-shaped staples and staple drivers serving to drive the staples out of the staple grooves during the stapling procedure.
The staple drivers drive the staples by interacting with a pointed wedge adapted to move along the working section of the staple case.
The wedge is arranged at the end of a plate turned toward the working section of the staple case. The other end of the plate mates with a carriage seated in the groove in the staple case and adapted for longitudinal movement therethrough.
The thrust case also incorporates a working section disposed opposite the working section of the staple case. The working section of the thrust case mounts an anvil serving as a thrust receiver of the staples being ejected and bent at the free ends thereof.
For this purpose, the anvil is provided with two rows of sockets disposed along the full length of the thrust case working section opposite the staple grooves in the staple case working section when the stapling apparatus is in the assembled state.
The detent of the staple and thrust cases of the prior art surgical stapling apparatus is devised in the form of a gear rack. In mating the staple and thrust cases, teeth of the gear rack couple in succession and individually lock the working sections relative to each other, and, thus, permit adjusting the suture clearance according to the thickness of biological tissue being joined.
It is known to those skilled in the art that the suture clearance is defined as the distance between the surfaces of the surgical stapling apparatus working sections which interact with biological tissue during the stapling procedure.
In said surgical stapling apparatus, the wedge interacting with the staple drivers is longer than normal because the wedge point point angle appropriate for suturing and resisting the staple forming force may not be more than 15 deg. This feature obstructs making a suture through the full length of the working section because distal ends of the working sections must be long enough to mount the long-size wedge.
There is also known a surgical stapling apparatus (cf. USSR Inventor's Certificate No. 886897) which is the closest analogue to the surgical stapling apparatus of the present invention.
The foregoing surgical stapling apparatus comprises a thrust case and a staple case. The staple case incorporates a lengthwise groove formed by side walls of the working section.
The lengthwise groove accommodates a magazine shaped on the outside identically with the interior of the lengthwise groove. The magazine holds a plurality of U-shaped staples charged evenly in sockets along the full length of the magazine.
The same sockets accommodate staple drivers. Each driver is devised as a right-angle prism, the slant surface whereof faces a magazine bottom surface, and the opposite flat end thereof faces the staples driver thereby.
A handle in assembly with a ring attached to the staple case permits holding the surgical stapling apparatus by the hand. The staple drivers interact with a pointed wedge adapted for movement along the working section of the staple case.
The wedge is mounted at an end of a plate facing the working section of the staple case. The opposite end of the plate is linked with a carriage movable along the groove in the staple case.
The thrust case incorporates a working section disposed opposite the working section of the staple case when the cases are in mated state. A groove provided in a the working section of the thrust case along the full length thereof is formed by side walls of the working section.
The above groove accomodates an anvil incorporating sockets, serving as a thrust receiver of the staples being ejected, and permitting bending the free ends thereof for suturing biological tissue.
A suture clearance adjustment device located in the working section of the thrust case permits moving the anvil in parallel in the direction of the staple case working section, with the result that the suture clearance can be adjusted within a certain range.
The suture clearance adjustment device comprises a crank shaft carrying a knob serving to turn the crankshaft.
The anvil is devised in the form of a right-angle prism, the side surface whereof facing the working section of the staple case and serving to compress biological tissue being sutured incorporates sockets disposed opposite similar sockets in the magazine. A lengthwise groove in the die accommodates a crank of the crankshaft.
When the crankshaft is turned by the knob, the anvil moves toward the working section of the staple case and thus regulates the distance between the cooperation surfaces serving to compress biological tissue, and the working section of the staple case.
The above-mentioned feature of the prior-art surgical stapling apparatus permits adjusting the suture clearance.
The thrust case also carries a handle with a ring which permits holding the case by the hand.
The foregoing surgical stapling apparatus also incorporates a sectional hinge joint and a detent, serving for interconnection of the thrust and staple cases. The sectional hinge joint is disposed in the area of interconnection of the working sections of the staple and thrust cases, and is furnished with a shaft attached to the staple case and introduced into a hole in the thrust case at one end thereof.
The case detent is essentially a double-gear rack disposed beside the handle and ring assemblies.
In the prior-art surgical stapling apparatus, the length of the working sections of the thrust and staple cases is extended to permit arrangement at the distal ends thereof of a long-size wedge having a point angle of not more than 15 deg, and a journal of the crankshaft incorporated in the suture clearance adjustment device.
The above-mentioned relatively high pointing of the wedge, and, hence, the extended length of the working parts of the surgical stapling apparatus are necessary to permit movement of the staple drivers interacting with the wedge, and to permit bending the staples during the suturing procedure.
It has been known (for example, cf. Periodical KHIRURGICHESKIE SSHIVAYUSCHIE APPARATY (Surgical Suturing Apparatus, in Russian), Edition VII, VNIIKHAI, Moscow, 1967, pp.13-15) that the relationship between the staple forming force and the suture clearance depending on the thickness of tissue being joined shows that the staple forming force gradually increases in the region near the minimum suture clearances, and with further reduction of the suture clearances, said force rises abruptly with the result that the operator's effort increases, and, hence, the dimensions of the surgical stapling apparatus working sections must be rather large.
In the prior-art surgical stapling apparatus wherein the wedge point angle is constant, no allowance is made for the nature of growth of forces required to form each staple during the suturing procedure, whereby the surgical stapling apparatus of large size cannot be efficiently used in suturing operative incisions.
The principal object of the present invention is to provide a surgical stapling apparatus, wherein the construction of the wedge will permit reducing the length of the whole surgical stapling apparatus.
Another object of the invention is to provide a surgical stapling apparatus, the construction whereof will improve the service reliability and the operating efficiency thereof in stitching surgical incisions.
A further object of the invention is to provide a surgical stapling apparatus of substantially simplified construction.
With these and other objects in view, a surgical stapling apparatus herein proposed comprises a thrust case and a staple case incorporating a groove formed by the side walls thereof and accommodating a magazine containing staples, staple drivers and a wedge interacting with the staple drivers in ejecting the staples and seating on a carriage supported in guides running along the staple case, with the thrust case furnished with an anvil serving as a thrust receiver of the staples being ejected and bent at the free ends thereof, and also comprises a sectional hinge joint and a sectional detent interconnecting the thrust and staple cases, and a suture clearance adjustment device, wherein, according to the invention, a wedge surface interacting with the staple drivers is curvilinear, with lines tangent to the generatrix thereof and a travelling direction of the wedge located so as to constitute an angle varying gradually from 45 deg to zero between a front part of the wedge and the back part thereof in the direction of the wedge travel during the stapling procedure.
The foregoing wedge surfaces interacting with the drivers are devised so as to permit reducing the wedge length and, hence, the overall dimensions of the working section distal ends extending beyond the suture line, and also to permit reducing the operator's effort.
The above-mentioned angle range from 45 deg to zero is optimum and is determined by the nature of variation of the force required for forming each staple during interaction between the respective staple driver and the wedge curvilinear surface because the forces required for ejecting the staple and piercing the tissue at the initial phase of interaction are not high and are commensurate with the forces normally applied by the operator during movement of the wedge.
At later stages of interaction between the curvilinear surface of the wedge and the staple driver, the staple forming forces are increased and are compensated by the force exerted by the wedge at a respective slope angle between the tangent and the wedge curvilinear surface, which is vertically a wedge point angle in the given area of the curvilinear surface.
Though the staple forming force rises abruptly at the final staple forming stage of the suturing procedure, the operator's effort is not to be increased because the wedge point angle is zero in the wedge back part.
If the angle between the tangent and the wedge curvilinear surface in the front part of the wedge is more than 45 deg, the force to be applied by the operator for moving the wedge will exceed the force required for initial ejection of the staple and for piercing the tissue by the tabs thereof.
If the angle between the tangent and the curvilinear surface in the front part of the wedge is less than 45 deg, the wedge overall length increases, with the result that the dimensions of the working sections of the surgical stapling apparatus must be increased also, whereby difficulties arise in making the sutures along the full length of the surgical stapling apparatus working section and in operating the surgical stapling apparatus in the suture area.
If the angle between the tangent and the curvilinear surface in the back part of the wedge is more than zero, it is impossible to develop a sufficient force exerted by the wedge when a maximum staple forming force is required during the suturing procedure.
If the angle between the tangent and the curvilinear surface in the back part of the wedge is less than zero, that is, if the angle is negative, the staple driver fails to eject the staple when the wedge moves and when the pusher interacts with the wedge, whereby the tissue cannot be pierced by the staple.
The surgical stapling apparatus of the present invention is relatively small-sized, and can be efficiently handled during surgical operations, with the result that jerking and irregular variation of the operator's efforts can be precluded in joining the tissue, and the manipulation of the apparatus introduced into the operative incision can be improved.